The long-range purpose of the project is to study the biochemistry, morphology, pharmacology and physiology of inner ear neurons and cells of their interactions and to describe the mechanisms of these interactions. 1. The techniques for total micro-amino acid analysis of picomole quantities of sample have been refined to permit the determination also of cysteine and cystine. 2. Two-dimensional electrofocusing/electrophoresis has been applied to the analysis of cochlear proteins. No consistent differences were seen between the normal and genetically deaf waltzing guinea pig in the protein patterns of the stria vascularis. 3. Results from application of alpha-bungarotoxin to cochlea strengthened the hypothesis that postsynaptic receptors of cochlear efferents are cholinergic and indicate that these receptors are different from most other kinds of cholinergic receptors at vertebrate synapses. 4. Autoradiography after in vitro incubation with the labeled amino acids H-GABA, 3-H-glutamate and 3H-aspartate showed heavy labeling over fibers and terminals of the efferent olivocochlear bundle.